Xanthine oxidase inhibition study of isolated secondary metabolites from Dolichandrone spathacea (Bignoniaceae): In vitro and in silico approach.

Xanthine oxidase (XO) has been widely recognized as a pivotal enzyme in developing hyperuricemia, primarily contributing to the excessive production of uric acid during purine metabolism in the liver. One of the standard treatment approaches involves reducing uric acid levels by inhibiting XO activity. In this study, the leaf extract of Dolichandrone spathacea, traditionally used in folk medicine, was found to inhibit XO activity in the ethyl acetate and butanol fractions at a concentration of 100 µg/mL, their values were 78.57 ± 3.85 % (IC50 = 55.93 ± 5.73 µg/ml) and 69.43 ± 8.68 % (IC50 = 70.17 ± 7.98 µg/ml), respectively. The potential XO inhibitory components were isolated by bioactivity assays and the HR-ESI-MS and NMR spectra system. The main constituents of leaf extracts of Dolichandrone spathacea, six compounds, namely trans-4-methoxycinnamic acid (3), trans-3,4-dimethoxycinnamic acid (4), p-coumaric acid (5), martynoside (6), 6-O-(p-methoxy-E-cinnamoyl)-ajugol (7), and scolymoside (17), were identified as potent XO inhibitors with IC50 values ranging from 19.34 ± 1.63 µM to 64.50 ± 0.94 µM. The enzyme kinetics indicated that compounds 3-5, 7, and 17 displayed competitive inhibition like allopurinol, while compound 6 displayed a mixed-type inhibition. Computational studies corroborated these experimental results, highlighting the interactions between potential metabolites and XO enzyme. The hydrogen bonds played crucial roles in the binding interaction, especially, scolymoside (17) forms a hydrogen bond with Mos3004, exhibited the lowest binding energy (-18.3286 kcal/mol) corresponding to the lowest IC50 (19.34 ± 1.63 µM). Furthermore, nine compounds were isolated for the first time from this plant. In conclusion, Dolichandrone spathacea and its constituents possess the potential to modulate the xanthine oxidase enzyme involved in metabolism.

New Trichothecenes Isolated from the Marine Algicolous Fungus Trichoderma brevicompactum.

Eight trichothecenes, including four new compounds 1-4 and four known entities 5-8, together with one known cyclonerane (9) were isolated from the solid-state fermentation of Trichoderma brevicompactum NTU439 isolated from the marine alga Mastophora rosea. The structures of 1-9 were determined by 1D/2D NMR (nuclear magnetic resonance), MS (mass spectrometry), and IR (infrared spectroscopy) spectroscopic data. All of the compounds were evaluated for cytotoxic activity against HCT-116, PC-3, and SK-Hep-1 cancer cells by the SRB assay, and compound 8 showed promising cytotoxic activity against all three cancer cell lines with the IC50 values of 3.3 ± 0.3, 5.3 ± 0.3, and 1.8 ± 0.8 µM, respectively. Compounds 1-2, 4-6, and 7-8 potently inhibited LPS-induced NO production, and compounds 5 and 8 showed markedly inhibited gelatinolysis of MMP-9 in S1 protein-stimulated THP-1 monocytes.

Fast dereplication of xanthine oxidase-inhibiting compounds in alfalfa using comparative metabolomics.

Xanthine oxidase (XO) inhibition is a major strategy for preventing hyperuricemia and associated comorbidities, such as gout. Alfalfa extract has been demonstrated to possess XO-inhibiting activity; however, the elaborate conventional fraction-by-fraction analyses hindered the identification of the active components. In this study, we established a streamlined approach to rapidly screen, identify, and characterize XO-interacting compounds in alfalfa, by incorporating protein-subtraction, mass profiling, and molecular docking analysis. Crude extract was incubated with or without XO protein before UPLC-ESI-Q-TOF-MS/MS composition profiling. By dereplicating the component profile of XO-subtracted extract from that of untreated extract, the targets were rapidly narrowed down to twelve XO-interacting compounds, regarded as potential xanthine oxidase inhibitors (XOIs). Molecular docking analysis revealed that nine of these compounds, namely salicylic acid, tricin 7-O-glucuronopyranoside, chrysoeriol-7-glucoside, ferulic acid, apigenin 7-O-ß-glucuronopyranoside, apigenin, tricin, chrysoeriol, and liquiritigenin, exhibited high affinity with XO, and depicted the possible mechanisms of inhibition. In vitro bioassay further verified the XO inhibitory activities of selected compounds, among which apigenin, chrysoeriol and liquiritigenin were more potent XO inhibitors (XOIs), with IC50 of 0.25, 0.5 and 1 µM, respectively, compared to allopurinol (IC50 = 1.41 µM), the well-known XO-inhibiting drug. Together, the results demonstrated that alfalfa is a promising natural source for potent XOIs which might be applied for nutraceuticals development and that the approach used is applicable for efficient screening, identification, and mechanistic analyses of enzyme-inhibiting compounds from plant-based resources.

Melanogenesis Inhibitors from the Rhizoma of Ligusticum Sinense in B16-F10 Melanoma Cells In Vitro and Zebrafish In Vivo.

The rhizoma of Ligusticum sinense, a Chinese medicinal plant, has long been used as a cosmetic for the whitening and hydrating of the skin in ancient China. In order to investigate the antimelanogenic components of the rhizoma of L. sinense, we performed an antimelanogenesis assay-guided purification using semi-preparative HPLC accompanied with spectroscopic analysis to determine the active components. Based on the bioassay-guided method, 24 compounds were isolated and identified from the ethyl acetate layer of methanolic extracts of L. sinense, and among these, 5-[3-(4-hydroxy-3-methoxyphenyl)allyl]ferulic acid (1) and cis-4-pentylcyclohex-3-ene-1,2-diol (2) were new compounds. All the pure isolates were subjected to antimelanogenesis assay using murine melanoma B16-F10 cells. Compound 1 and (3S,3aR)-neocnidilide (8) exhibited antimelanogenesis activities with IC50 values of 78.9 and 31.1 µM, respectively, without obvious cytotoxicity. Further investigation showed that compound 8 demonstrated significant anti-pigmentation activity on zebrafish embryos (10‒20 µM) compared to arbutin (20 µM), and without any cytotoxicity against normal human epidermal keratinocytes. These findings suggest that (3S,3aR)-neocnidilide (8) is a potent antimelanogenic and non-cytotoxic natural compound and may be developed potentially as a skin-whitening agent for cosmetic uses.